The invention relates to a method for weighing a load of a transport vehicle, the vehicle comprising a body, a loading platform, a plurality of wheels, a wheel suspension for supporting each wheel to the body, and the wheel suspension comprises at least one bogie structure including at least two axles connected to one another on either side of the vehicle by means of a horizontal arm, which horizontal arm is connected to the body by means of a vertical arm, and which method comprises: measuring vertical loads exerted on the wheel suspension, at least at three measurement points, each of which being provided with at least one sensor; conveying measurement data from the sensors to at least one calculating unit of weighing; and determining the weight of the load in the calculating unit on the basis of the measurement data obtained from the measurement points and the calculation parameters of the calculating unit.
The invention also relates to a transport vehicle comprising: a body, a loading platform, a plurality of wheels, a wheel suspension for supporting each wheel to the body, the wheel suspension comprising at least one bogie structure including at least two axles connected to one another on either side of the vehicle by means of a horizontal arm, which horizontal arm is connected to the body by means of a vertical arm, at least three measurement points for measuring vertical loads exerted on the wheel suspension by means of at least one sensor locating at each measurement point, and at least one calculating unit of weighing that is arranged to determine the weight of the load to be transported on the basis of the measurement results obtained from the measurement points.
The invention further relates to a bogie structure of a transport vehicle. The bogie structure comprising: at least a first axle and a second axle, at least a first horizontal arm and a second horizontal arm for connecting the axles to one another on either side of the vehicle, and at least a first vertical arm for connecting the first horizontal arm to the body of the vehicle and at least a second vertical arm for connecting the second horizontal arm to the body of the vehicle.
Extremely heavy transport vehicles are employed at mining and excavation sites for moving rock material. In order that the working site could be appropriately managed and the material flow of the site controlled the amount of moved material should be generally known. So, the payload transported by a vehicle is weighed. Weighing may be carried out by driving the transport vehicle to an on-site weighing station, which makes the operation slower and more cumbersome, however. Alternatively, each transport vehicle may be provided with a specific weighing apparatus. In that case the weighing may take place during loading or transfers. In addition, vehicle-specific weighing may prevent an excessive charge from being loaded onto the transport vehicle, and thus it is possible to avoid damage and premature wear caused to the vehicle. It is previously known to determine the weight of the vehicle payload by measuring the pressure in the lift cylinders of the loading platform. In addition, in some cases there are measured loads exerted on the tipping hinges of the loading platform. A drawback with the weight measurements based on the platform support points is, however, that the position of the gravity centre of the charge on the platform clearly affects the accuracy of the measurement results. Moreover, for the duration of the weighing the platform has to be lifted to rest on lift cylinders, which means that the weighing can be carried out only when the transport vehicle is stationary, because when the platform is lifted to rest on the lift cylinders, the body of the vehicle is subjected to heavy loads, which together with dynamic loads may damage the body of the transport vehicle. Therefore, the weighing based on measuring the platform support points is inaccurate and slow. It is also known to determine the payload of a transport vehicle by measuring the load exerted on the wheel suspension trunnions of the vehicle. In that case as well inaccuracy in measurement poses a problem, because the measurement results depend on the position in which the wheels of the vehicle have been turned. In order for the measurement to be reliable the wheels should always be turned in a given predetermined position during the measurement. Naturally this makes it slower and more difficult to carry out the weighing. All in all, the known weighing solutions have a drawback that their accuracy in measurement is not sufficient and the weighing is difficult and slow to perform.